"unresolved external symbol" error in Visual Studio 2013 - c++

Question

I am trying to use the libnoise library, which is a c++ library for perlin noise generation, in Visual Studio 2013. Tutorial 3 links to an addon utility called noiseutils, which consists of a .cpp and a .h, which I place here:
I have the project settings pointed towards the include folder (whose contents are in the image below), and my code looks like this.
#include "stdafx.h"
#include <noise/noise.h>
#include "noiseutils.h"
int _tmain(int argc, _TCHAR* argv[])
{
noise::module::Perlin myModule;
utils::NoiseMap heightMap;
utils::NoiseMapBuilderPlane heightMapBuilder;
heightMapBuilder.SetSourceModule(myModule);
heightMapBuilder.SetDestNoiseMap(heightMap);
heightMapBuilder.SetDestSize(256, 256);
heightMapBuilder.SetBounds(2.0, 6.0, 1.0, 5.0);
heightMapBuilder.Build();
utils::RendererImage renderer;
utils::Image image;
renderer.SetSourceNoiseMap(heightMap);
renderer.SetDestImage(image);
renderer.Render();
utils::WriterBMP writer;
writer.SetSourceImage(image);
writer.SetDestFilename("tutorial.bmp");
writer.WriteDestFile();
return 0;
}
All of that code is given in the third tutorial provided on their website. Visual Studio has no complaints that it cannot find any of the classes or functions specified in all of this code. However, when I try to build the project...
1>------ Build started: Project: libnoisetest, Configuration: Debug Win32 -- ----
1> libnoisetest.cpp
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.h(1217): warning C4244: 'initializing' : conversion from 'const double' to 'float', possible loss of data
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::GradientColor::~GradientColor(void)" (??1GradientColor#utils#noise##QAE#XZ) referenced in function "public: __thiscall noise::utils::RendererImage::~RendererImage(void)" (??1RendererImage#utils#noise##QAE#XZ)
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::NoiseMap::NoiseMap(void)" (??0NoiseMap#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::NoiseMap::~NoiseMap(void)" (??1NoiseMap#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::Image::Image(void)" (??0Image#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::Image::~Image(void)" (??1Image#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: void __thiscall noise::utils::WriterBMP::WriteDestFile(void)" (?WriteDestFile#WriterBMP#utils#noise##QAEXXZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::NoiseMapBuilderPlane::NoiseMapBuilderPlane(void)" (??0NoiseMapBuilderPlane#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: virtual void __thiscall noise::utils::NoiseMapBuilderPlane::Build(void)" (?Build#NoiseMapBuilderPlane#utils#noise##UAEXXZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: __thiscall noise::utils::RendererImage::RendererImage(void)" (??0RendererImage#utils#noise##QAE#XZ) referenced in function _wmain
1>libnoisetest.obj : error LNK2019: unresolved external symbol "public: void __thiscall noise::utils::RendererImage::Render(void)" (?Render#RendererImage#utils#noise##QAEXXZ) referenced in function _wmain
1>B:\Visual Studio\_Projects\libnoisetest\Debug\libnoisetest.exe : fatal error LNK1120: 10 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
In short, Visual Studio can't find any of the stuff in "noiseutils" while it's actually building. What am I doing wrong here?
UPDATE:
After copying noiseutils.cpp to my source folder as suggested by Praetorian, I get this set of warnings, and a single error:
1>------ Build started: Project: libnoisetest, Configuration: Debug Win32 ------
1> noiseutils.cpp
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.cpp(24): warning C4627: '#include <fstream>': skipped when looking for precompiled header use
1> Add directive to 'stdafx.h' or rebuild precompiled header
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.cpp(26): warning C4627: '#include <noise/interp.h>': skipped when looking for precompiled header use
1> Add directive to 'stdafx.h' or rebuild precompiled header
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.cpp(27): warning C4627: '#include <noise/mathconsts.h>': skipped when looking for precompiled header use
1> Add directive to 'stdafx.h' or rebuild precompiled header
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.cpp(29): warning C4627: '#include "noiseutils.h"': skipped when looking for precompiled header use
1> Add directive to 'stdafx.h' or rebuild precompiled header
1>b:\visual studio\extra libraries\libnoise\include\noiseutils.cpp(1303): fatal error C1010: unexpected end of file while looking for precompiled header. Did you forget to add '#include "stdafx.h"' to your source?
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
I looked up this problem and discovered that I can simply disable using precompiled headers for noiseutils.cpp since it doesn't need access to stdafx. With that, problem solved.
Out of curiosity though, what is stdafx and what role does it play in a Visual Studio project? Would I need to disable precompiled headers for any source code that I add to my project so that it ignores stdafx?

Answer 1

Right click -> Proprieties -> C++ -> Additional Include Directories and add your headers location
Right click -> Add -> Existing Item -> Add your files
If you want
Right click -> Add -> New Filter and you put the files there